URGENT HELP PLEASE! 1.6 FSi cooling problem - head gasket?

Barryt0

A2OC Donor
Hi all,

Upon starting my FSi one morning recently I had the Low Coolant warning on the dash. I tried topping up the expansion tank, only to hear it gushing out as quickly as I was pouring it in. I called out the RAC, who couldn't get a good enough view to see where the leak was, other than to say it was somewhere near the water pump. So I had the car towed to my local garage, where they identified a plastic pipe running along the back of the engine has cracked, hence losing coolant. The garage replaced the pipe, took the car on a test drive and the temp gauge reached 90° and stayed there (as it should), but they could hear the coolant boiling up, and the hoses felt overly pressurized. It seems that the thermostat isn't opening, so they tried replacing it, but this made no difference. They've tried 3 thermostats, still with no difference. Temp gauge stays at 90°.

They now believe the head gasket may have blown, or the head warped or cracked. Best case scenario £600 ish. Worst case... who knows.

My question is, which issue is the cause, and which is the result? If the head gasket has blown (as they suspect) resulting in the coolant system over-pressurizing, might that explain why the plastic pipe cracked, leading to the loss of coolant? Or if the pipe cracked first, emptying the coolant, is that what caused the head gasket to blow? If so, why did the pipe crack in the first place? Either way, why doesn't the temp gauge read higher than normal?

The reason I ask is that if the head gasket blew first, I can claim on a warranty. If the pipe blew first, I can't.

Any ideas gratefully received.
 
That particular plastic pipe is something that seems to crack often.

It is the source of many reported leaks on here.

So the chances are that it broke first.
As for a blown head gasket causing it to crack under pressure? If the pipe was OK it would have held under that pressure. The excess pressure would leak from the filer cap before exploding a pipe.

What evidence is there to suggest that there is a head gasket problem now that the pipe has ben fixed?

I have never heard of anyone saying that you can hear the water boiling in the pipes???

That statement sounds odd, it might just be an air lock that is causing the noise?

As for the pipes being under pressure, this is normal, as the water heats it expends, so there is pressure in the system anyway.



Evidence of a head cgasket failure includes

Steam from the overheated water being visible and loosing the coolant.
Overheating
Excess steam in the exhaust.
Water in the oil and/or oil in the water.
etc.

I have never heard a head gasket priblem being diagnosed from a "boiling sound" (unless there is steam everywhere.

Try running the engine hot with the coolant filler cap off (Only ever take the cap off when the engine is cold!!!)
This will do two things, firstly you should be able to see if there are any bubbles / air / oil in the coolant
Secondly, if there is an air lock this will release it and the coolant level will drop due to the air now escaping.

If the engine does not overheat while doing this, put the cap on and drive around the block keeping a close eye on the temperature. Keep driving it around the block until it is clear that the temperature gauge is staying steady or until it raises and then return home.

If the head gasket has gone you will see the car overheat, that is for sure, if it doesn't overheat, then leave it as it is and carefully use the car as normal keeping an eye on the gauge.

Steve B
 
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As for the warranty, yes most warranties with exclude coolant hoses, but are you sure that includes solid (albeit plastic) pipes? I am not so sure.

The pipe breking is a mechanical failure, unlike a coolant hose leaking, there is a difference, so please check the wording closely.
Any warranty that covers you for a head gasket failure should also cover you for fractured pipes (although some of the worst warranties will try anything to get ot of paying out for a claim)

Steve B
 
Thanks for the speedy, and detailed response Steve. Much appreciated!

I suppose the only 'evidence' of the failed head / head gasket the garage have offered is the 'over-pressurised' cooling system and the thermostat not opening. I may have been wrong about them 'hearing' the coolant boiling, though I thought that's what they said...

The warranty is an RAC policy. Under 'Cooling System' it states that pipes and hoses aren't covered, but there are no other exclusions so a head gasket or warped head should be covered, unless it was due to a pipe or hose failing. The garage say the temp gauge stays on 90°, but they think it's running hotter than that. They seem convinced that the thermostat isn't opening, so have currently removed and bypassed it.
 
The problem you have is that there is currently no proof that anything is actually wrong.

The mechanic "thinking" that it is running hot and the pipes "might" be over pressurised is not enough to prove anything, least of all to the insurance company. The problem with that is that the cylinder head would have to be removed to check to see if it was a head gasket problem and if the garage strip it down and it is NOT blown, you will have to pay for a strip down and rebuild and STILL have the same symptoms.

Running without a thermostat is not recomended, the engine may never get up to the right temperature or will take a lot longer to get there.

If it has not actually overheated and there are no other symptoms then surely it would be better to run it for a while and see if it overheats?

Also if they have tried three different thermostats and they are saying that they are still not opening, then surely they can't believe that all three new thermostats are broken?

You really do need to try to get it as hot as you can and see if it holds at 90 without blowing steam out of the filler cap.

Steve B
 
Hi sorry to hear your issues. One other point to check is- is there a good flow of coolant? As its not unheard of that the standard Audi water pump to fail in such away that the impeller cracks and no longer drives the water around. This would lead to the water boiling due to no flow of cooling water.
Cheers Mike
 
Hi,

just to add some extra information to this thread.

The FSI has an ECU controlled electric "thermostat" rather than the traditional mechanical temperature activated valve. The ECU control allows the engine to reach operating temperature quicker and stay there better than a mechanical thermostat and so improve engine efficiency.

The FSI thermostat is quite expensive part (was £150 last time I looked and that was many years ago) so I would be surprised if the garage have changed it 3 times on a whim.

The normal operating temperature for the FSI engine is higher than the non-FSI petrols and over 100 degrees C (up to 115 degrees C from memory). The "sanitised" gauge temperature shown is always 90 degrees no matter what kind of engine so drivers don't get scared by the true high temperature of the engine coolant. That's why the temperature sender has two sensors, one for the gauge and one for the true temperature for the ECU.

The cooling system additives allow the engine to run hotter than the boiling point of water without the coolant liquid boiling.

The ECU should open the "coolent regulator" valve to allow coolent to flow through the radiator to regulate the temperature prevent the engine overheating. If this isn't happening then the engine will overheat quite rapidly when driving. This could be caused by either the ECU not thinking the engine is warm (temperature sender problem) or the valve not opening when instructed ("coolent regulator" - "thermostat") problem. Either of these should be fairly easy to diagnose.

If the coolant is boiling a the correct operating temperature then perhaps the wrong additive has been used or there is a flow problem (e.g. blockage or pump problem).

regards

Andrew
 
Understood. I'll have to ask for more information. Maybe the bottom hose is cold... I don't know.

Where is the temp gauge on the FSi? Is it possible that it will give a normal reading while part of the engine is actually running hotter?

They don't believe that 3 thermostats can be faulty, no. They're a pretty good outfit so I assume (!) they would only try them if they thought it was a possibility. They won't be charging me for them anyway...! They believe the coolant isn't circulating properly, so the thermostat isn't opening, and they conclude that this must be due to a leak from the gasket or head itself.
 
Hi,

just to add some extra information to this thread.

The FSI has an ECU controlled electric "thermostat" rather than the traditional mechanical temperature activated valve. The ECU control allows the engine to reach operating temperature quicker and stay there better than a mechanical thermostat and so improve engine efficiency.

The FSI thermostat is quite expensive part (was £150 last time I looked and that was many years ago) so I would be surprised if the garage have changed it 3 times on a whim.

The normal operating temperature for the FSI engine is higher than the non-FSI petrols and over 100 degrees C (up to 115 degrees C from memory). The "sanitised" gauge temperature shown is always 90 degrees no matter what kind of engine so drivers don't get scared by the true high temperature of the engine coolant. That's why the temperature sender has two sensors, one for the gauge and one for the true temperature for the ECU.

The cooling system additives allow the engine to run hotter than the boiling point of water without the coolant liquid boiling.

The ECU should open the "coolent regulator" valve to allow coolent to flow through the radiator to regulate the temperature prevent the engine overheating. If this isn't happening then the engine will overheat quite rapidly when driving. This could be caused by either the ECU not thinking the engine is warm (temperature sender problem) or the valve not opening when instructed ("coolent regulator" - "thermostat") problem. Either of these should be fairly easy to diagnose.

If the coolant is boiling a the correct operating temperature then perhaps the wrong additive has been used or there is a flow problem (e.g. blockage or pump problem).

regards

Andrew

Ok, that's interesting. I'll forward this on to the garage.

Thanks Andrew.
 
Understood. I'll have to ask for more information. Maybe the bottom hose is cold... I don't know.

Where is the temp gauge on the FSi? Is it possible that it will give a normal reading while part of the engine is actually running hotter?

They don't believe that 3 thermostats can be faulty, no. They're a pretty good outfit so I assume (!) they would only try them if they thought it was a possibility. They won't be charging me for them anyway...! They believe the coolant isn't circulating properly, so the thermostat isn't opening, and they conclude that this must be due to a leak from the gasket or head itself.

The only way to see what the "true" temperature is (as far as the car is concerned) is to interrogate the engine ECU measured values using a diagnostic tool (e.g. VAG-COM). This will report what value in degrees C that the ECU is reading off the temperature sender. If this is sensible then the temperature sender is OK but if it is underreported (too low) when obviously the actual coolant liquid is much hotter then there is a problem with the temperature sender.

regards

Andrew
 
Hi sorry to hear your issues. One other point to check is- is there a good flow of coolant? As its not unheard of that the standard Audi water pump to fail in such away that the impeller cracks and no longer drives the water around. This would lead to the water boiling due to no flow of cooling water.
Cheers Mike

Thanks Mike.

It's not a genuine Audi water pump. When I bought the car there was a receipt for cambelt & water pump from an independent garage. Probably even more likely to fail I guess...?

I think I've written off the idea that I can claim on the RAC warranty, as buried further in the Ts & Cs it states that any claim arising due to overheating isn't covered. Useless!

I'm vaguely clinging onto to the hope that there isn't really a problem, and the garage are fussing over nothing. Slim chance eh?! I wonder if I can drive it as far as the nearest:
a) cliff
b) field (where I can set light to it)
c) car sales forecourt (where I can trade it in for something less temperamental).
 
A good garage will be able to sniff test the coolant whils it's running and that will show if combustion gasses are passing into the coolant channels. I'm curious as to why they sY they have tried 3 thermostats as the Fsi thermostat is not easy to get to and I have always changed as an assembly-that isn't cheep at circa £100. Cheers Mike
 
I hate the "insurance" type of warranty, they always seem to find a way to not pay out.

When you say something less Temperamental, that should perhaps be something less "Temperature Mental" (Sorry for the attempt at humour at a time like this but I rarely miss the opportunity to Pun)

It really does sound like it could be a failed water pump as Mike suggested. That would give such symptoms.

We all have our fingers crossed for you.

Steve B
 
Possible water pump failure. I would guess that the propellor has broken and the heat of the water has caused the pipe fracturing.

Same thing happened to mine. New pipe and water pump.

Also have the car scanned for faults before doing any more work.
 
UPDATE

I popped in to the garage last night, and can clarify a few things:

1) The bottom hose remains cold, and all hoses become 'overly pressurized' (though this is subjective I suppose; they might not know what is 'normal' for this particular engine). This leads them to believe that exhaust gases are getting into the coolant system, most likely via a crack.
2) They HAVE tried 3 new thermostats; 2 OE and one genuine Audi. They've had the car for nearly 2 weeks, so I have no reason not to believe them. Disconnecting the wiring to the thermostat returns a fault, so they believe the wiring is OK.
3) Coincidentally I asked them, while they had the car, to change the water pump and cambelt. As such they inspected the old pump and found it to be fine; no obvious damage.

I was first aware of a problem when I tried topping up the coolant one morning and it immediately leaked out all over the drive. The day before the car had been on a good run, during which I do remember hearing a 'gushing' noise from the engine, that lasted for only a second. I distinctly recall it, as I stopped mid-sentence and asked my wife if she heard it, which she did. There were no other signs of a problem though; temperature gauge stayed at 90° and the low coolant warning didn't appear until the following day.
 
I hate the "insurance" type of warranty, they always seem to find a way to not pay out.

When you say something less Temperamental, that should perhaps be something less "Temperature Mental" (Sorry for the attempt at humour at a time like this but I rarely miss the opportunity to Pun)

It really does sound like it could be a failed water pump as Mike suggested. That would give such symptoms.

We all have our fingers crossed for you.

Steve B

Steve,

Me too. Thankfully it didn't cost a lot. The wording states that claims resulting from 'overheating' are not covered, but the temp gauge never rose about 90°, so I'm going to try it on with them.

Barry
 
A good garage will be able to sniff test the coolant whils it's running and that will show if combustion gasses are passing into the coolant channels. I'm curious as to why they sY they have tried 3 thermostats as the Fsi thermostat is not easy to get to and I have always changed as an assembly-that isn't cheep at circa £100. Cheers Mike

Cheers Mike,

I'll ask them if they've had a sniff yet!

Barry
 
UPDATE

The saga continues...

I still haven't got the car back. They had already tried the 'sniff test' that Mike suggested, which was inconclusive; they said there would need to be a major breach in order to smell the exhaust gases in the coolant; a minor leak might not be detectable that way.

After several conversations, we concluded that the plastic pipe that 'burst' would only have done so if the pressure was too high in the cooling system, most likely due the head gasket failure. Otherwise the expansion tank filler cap would surely have blown first. This suggests that the circulation problem / head gasket failed first, resulting in the pressure build up, then the pipe burst, subsequently resulting in the loss of coolant. The RAC have said that, if that is the case, they will 'consider a claim'. However I have to pre-authorise the garage (to the tune of £718) to strip the head off to confirm the fault.

If the RAC don't pay out, I will end up with a bill in the region of £1,150. How much is the car worth again...?!
 
HI Barry,

sorry to hear that the problem is still not resolved, but if they are accepting that the head gasket may have caused the burst pipe then that has helped your claim (although I don't believe that to be the cause)

I am not sure that I agree with the garage about the sniff test either. If the leak into the coolant system was so small that it could not be detected, then how come the pressure was so high as to burst the pipe or cause serious overheating.

But the strip down will hopefully resolve the problem. Even if no head gasket problem is found, the strip down and rebuild should resolve it anyway (with luck)

Steve B
 
Sorry to jump on an old thread but it's more economical than starting a new one...

I have had exactly the same symptoms: firstly a rubber hose blew, then it was the black pipe of death. Luckily I had a fuel injector, cambelt and water pump to replace so the job wasn't so bad... Annoying that I had the thermostat housing out, though, and now potentially have to take it all out again!

Does the MAP controlled stat move the mechanical one open and closed? I'm thinking of changing the spring thermostat with a known working spare that I have but it may not repair the electronics if that's what's broken.

Anyone been here before please?
 
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